There are many cases where it is imperative to establish one-way visual contact in a field environment, in both emergency and -operational situations.
For example, it is known that individuals who are lost or stranded in unpopulated locations have need to increase their visibility to searchers especially to those who may be attempting to locate them. Aircraft are commonly used for search and rescue (SAR) operations, due to their obvious ability to view large areas from an altitude. However, it is also well known that the very distance and expanse of the view renders it difficult for personnel to spot an individual from an aircraft, the problem akin to finding a needle in a haystack. Consequently, a number of approaches have been adopted over the years to increase the visibility of an individual (or group of individuals) to searching aircraft, with varying degrees of success and also varying disadvantages.
One of the most basic is the use of a small mirror to reflect sunlight towards the aircraft. This approach is highly effective under optimal circumstances, such as when signaling an aircraft from a raft in the ocean under clear skies and bright sunlight. It is much less effective, however, under cloudy or rainy conditions or in wooded areas. Furthermore, it requires the vigilance and active participation of the individual, who may be sleeping or otherwise unaware as the aircraft passes over, and who may also be suffering from the effects of exhaustion, exposure and/or injuries that would impair the individual's alertness and ability to use the mirror. Moreover, a degree of skill is required to angle the mirror so as to direct the reflected sunlight towards the aircraft, which is all the more difficult when the aircraft can be glimpsed only briefly between trees or other cover. Yet another drawback of signaling mirrors is that they must be quite small (only a couple of inches on a side) in order to be sufficiently compact to be carried, which necessarily limits the size of the reflective surface that can be presented towards the observer.
Other “active” signals have also been used for many years, including various types of flairs and smokes. However, these signals have a very limited duration (from several seconds to a few minutes) and once expended can no longer be used. Moreover, their bulk and weight renders it impractical for an individual to carry more than one or two at most. Hence, their use has generally been limited to boats, rafts and other vessels/vehicles having a substantial carrying capacity.
Various passive signals and visibility enhancements have also been adopted, i.e. signal enhancements that do not require active operation by the individual or individuals being sought. Examples include arranging blocks or logs in a large “X” in a clearing. Although helpful, the use of natural materials (presenting a low contrast against their surroundings) and the steady nature of such displays mean that they are nevertheless hard to spot. Moreover, any significant fatigue or injury to the individual would render it difficult to mange such objects in an adequately large display.
The further disadvantage of most prior approaches is that (with the exception of flairs and the like) they cannot be seen at night. Radar equipped search aircraft are available; however, conventional approaches generally present either inadequate radar cross-sections or returns that are indistinguishable from their surroundings. Infrared (IR) search equipment is also available for night use; however, the IR signature of a person is virtually indistinguishable from that of a deer or many other large animals.
Yet another factor is that under some circumstances, particularly military operations, it is critical that the signal be visible only to “friendly” observers and not others. For example, it is preferable that the position of a pilot downed in hostile territory be visible only to allied recovery personnel and not to enemy forces. In other instances, advance or Special Forces personnel may wish to indicate a certain site, such as a beach approach or drop area, with a marker that is visible only for those for whom the signal was intended.
Accordingly, there exists a need for an apparatus that enables an individual to establish a visual display that can be effectively seen by observers under a wide range of conditions. Furthermore, there exists a need for an apparatus that is easily deployed by an individual even if fatigued or injured, and that does not require active intervention by the individual once deployed. Still further, there is a need for such an apparatus that can be used effectively during both night and day. Still further, there exists a need for such an apparatus that produces official display that can be seen at long distance. Still further, there exists a need for such an apparatus that is compact and lightweight so as to be highly portable by an individual. Still further, there exists a need for such an apparatus that can be arranged in various ways to provide a variety of signals to the observer or observers. Still further, there exists a need for such an apparatus that can be configured to produce a display that is visible only to desired observers and not to others.